Hydrogenation process

ABSTRACT

Disclosed are heterogeneous processes (i) for the hydrogenation of a compound containing at least one unsaturated carbon-carbon bond, and (ii) for the hydro-dehalogenation of a compound containing at least one C—Cl, C—Br or C—I bond. The processes comprise reacting said compound with a hydrogenating agent and a heterogeneous hydrogenation catalyst in the presence of an ionic liquid.

[0001] This invention relates to hydrogenation processes, and theirproducts. As used herein, the term “hydrogenation” also includeshydro-dehalogenation.

[0002] Hitherto, hydrogenation reactions have been carried out inorganic solvents such as propan-2-ol. However, such solvents often needpromoters to be selective and it is still necessary to extract thereaction product(s) from the solvent.

[0003] The present invention aims to overcome these disadvantages andfurther, provides novel processes that allow hydrogenation reactions tobe performed with better selectivities than hitherto.

[0004] According to one aspect of the present invention, there isprovided a process for the catalytic hydrogenation of a compoundcontaining at least one unsaturated carbon-carbon bond, said processcomprising reacting said compound with a hydrogenating agent and aheterogeneous hydrogenation catalyst in the presence of an ionic liquid.

[0005] The invention further provides a process for thehydro-dehalogenation of a compound containing at least one C—Cl, C—Br orC—I bond, the process comprising reacting said compound with ahydrogenating agent and a heterogeneous hydrogenation catalyst in thepresence of an ionic liquid. Thus, the present invention includes aheterogeneous process for the hydro-dechlorination of a compound,wherein a compound containing at least one C—Cl bond, and ahydrogenation agent are admixed in the presence of an ionic liquid.

[0006] The invention may thus be defined in its first aspect as aheterogeneous process for the hydrogenation of unsaturated aliphaticcarbons in a compound, wherein the compound and a hydrogenating agentare admixed in the presence of an ionic liquid.

[0007] More than one ionic liquid or any combination of ionic liquidsmay be used in the present invention.

[0008] The term “ionic liquid” refers to a liquid that is capable ofbeing produced by melting a solid, and when so produced, consists solelyof ions. Ionic liquids may be derived from organic salts, especiallysalts of heterocyclic nitrogen-containing compounds, and such ionicliquids are particularly preferred for use in the processes of thepresent invention.

[0009] An ionic liquid may be formed from a homogeneous substancecomprising one species of cation and one species of anion, or can becomposed of more than one species of cation and/or anion. Thus, an ionicliquid may be composed of more than one species of cation and onespecies of anion. An ionic liquid may further be composed of one speciesof cation, and one or more species of anion.

[0010] Thus, in summary, the term “ionic liquid” as used herein mayrefer to a homogeneous composition consisting of a single salt (onecationic species and one anionic species) or it may refer to aheterogeneous composition containing more than one species of cationand/or more than one species of anion.

[0011] The term “ionic liquid” includes compounds having both highmelting temperature and compounds having low melting points, e.g. at orbelow room temperature (i.e. 15-30° C.). The latter are often referredto as “room temperature ionic liquids” and are usually derived fromorganic salts having pyridinium and imidazolium-based cations.

[0012] A feature of ionic liquids is that they have particularly low(essentially zero) vapour pressures. Many organic ionic liquids have lowmelting points (e.g. less than 100° C., particularly less than 100° C.,and around room temperature, e.g. 15-30° C. Some have melting pointswell below 0° C.

[0013] Ionic liquids may be regarded as consisting of two components,which are a positively charged cation and a negatively charged anion.Generally, any compound that meets the criteria of being a salt(consisting of an anion and cation) and which is fluid at or near thereaction temperature, or exists in a fluid state during any stage of thereaction can be defined as an ionic liquid especially suitable for usein the process of the present invention.

[0014] For example, suitable ionic liquids for use in the presentinvention include salts of alkylated or polyalkylated heteroarylcompounds, such as salts of alkylated pyridine, pyridazine, pyrimidine,pyrazine, imidazole, pyrazole, oxazole and triazole. Thus, examples ofsuitable ionic liquids include those having the following formula:

[0015] wherein

[0016] R^(a) is a C₁ to C₄₀ (preferably C₁ to C₂₀ and more preferably C₄to C₁₂) straight chain or branched alkyl group or a C₃ to C₈ cycloalkylgroup, wherein said alkyl or cycloalkyl group which may be substitutedby one to three groups selected from: C₁ to C₆ alkoxy, C₆ to C₁₀ aryl,CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃₀ alkaryl;

[0017] R^(b), R^(c), R^(d), R^(e) and R^(f) can be the same or differentand are each independently selected from H or any of the R^(a) groups asdefined above; and

[0018] A represents an anion having a charge n−; wherein n may be 1-3.Preferably, in the above compounds, n is 1.

[0019] Preferably, R^(a) is an unsubstituted alkyl or cycloalkyl groupas defined above. R^(b), R^(c), R^(d), R^(e) and R^(f) are preferablyhydrogen.

[0020] In preferred ionic liquids for use in the processes of thepresent invention, the cation is preferably 1,3-dialkylimidazolium.Other cations for this process include other substituted pyridinium oralkyl- or poly-alkylpyridinium, alkyl imidazolium, imidazole, alkyl orpoly-alkylimidazolium, alkyl or polyalkylpyrazolium, ammonium, alkyl orpolyalkyl ammonium, alkyl or poly-alkyl phosphonium cations.

[0021] The anion for the present processes is preferably a phosphate oramide. Other anions include sulfur-containing anions such as sulfate orsulphite, nitrogen-containing anions, such as nitrate, nitrite,alkylsulfate, or a chloride, bromide or other halide, hydrogensulfate,oxoanions of metals, selenium, tellurium, phosphorus, arsenic, antimony,bismuth based anions, and boron halide anions, such astetrafluoroborate, [BF₄].

[0022] Particularly preferred ionic liquids are imidazolium, pyridiniumor pyrazolium salts. Thus, ionic liquids useful for the process of thepresent invention include those based on imidazolium cations having theformula:

[0023] wherein

[0024] each R^(a) may be the same or different and each is independentlyselected from C₁ to C₄₀ straight chain or branched alkyl which may besubstituted by one to three groups selected from: C₁ to C₆ alkoxy, C₆ toC₁₀ aryl, CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃₀ alkaryl;

[0025] A represents one or more species of anion having charge n−; and nrepresents 1-3.

[0026] Also suitable for the processes of the present invention areionic liquids based on pyridinium cations having the formula:

[0027] wherein

[0028] R⁸ is selected from C₁ to C₄₀ straight chain or branched alkylwhich may be substituted by one to three groups selected from: C₁ to C₆alkoxy, C₆ to C₁₀ aryl, CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃₀alkaryl;

[0029] A represents one or more species of anion having charge n−; and

[0030] n represents 1-3.

[0031] Preferably, in the above ionic liquids, R^(a) is independentlyselected from C₁ to C₄₀, preferably C₁ to C₂₀, and even more preferably,C₄ to C₁₂, straight chain or branched alkyl.

[0032] Preferred ionic liquids include those of the above formulaewherein A represents a single species of anion having charge n−; anionshaving a charge of 1 are especially preferred.

[0033] Ionic liquids useful in the present processes include thosewherein A represents an anion selected from boron or phosphorusfluorides, NO₃, SO₄, HSO₄, HCO₃, [(CF₃SO₂)₂N], [AsF₆], alkylsulfonates,mono- or difluorinated alkyl sulfonates including perfluorinatedalkylsulfonates, carboxylic acid anions, fluorinated carboxylic acidanions and metal halides.

[0034] Especially preferred are ionic liquids having the above formulaewherein A represents an anion selected from [PF6], [BF₄], [OSO₂CF₃],[OSO₂(CF₂)₃CF₃], [OCO₂CF₃], [OCO₂(CF₂)₃CF₃], [OCO₂CH₃], nitrate,sulfate, hydrogen sulfate, hydrogen carbonate, acetate,trifluoroacetate, lactate, [(CF₃SO₂)₂N], [B(alkyl)₄] wherein each alkylcan be the same or different and can be any straight chain or branchedC₁ to C₁₀ alkyl (preferably C₁ to C₆ alkyl) group, [SbF₆]⁻ and [AsF₆].

[0035] Even more preferred are ionic liquids of the above formulaewherein A represents an anion selected from [PF₆], [BF₄], [OSO₂CF₃],[OSO₂(CF₂)₃CF₃], [OCO₂CF₃], [OCO₂(CF₂)₃CF₃], [OCO₂CH₃], [(CF₃SO₂)₂N],[B(alkyl)₄] wherein each alkyl can be the same or different and can beany straight chain or branched C₁ to C₁₀ alkyl (preferably C₁ to C₆alkyl) group, [SbF₆]⁻ and [AsF₆].

[0036] Other preferred ionic liquids include those wherein the anion isphosphate or an amide.

[0037] The anions [PF₆] (hexafluorophosphate), [BF₄] (tetrafluoroborate)and [(CF₃SO₂)₂N] {bis[(trifluoromethyl)sulfonyl]amide or bistriflimide)are particularly preferred, especially for the imidazolium- andpyridinium-ation-based ionic liquids.

[0038] In a first embodiment, the present invention provides a processfor the hydrogenation of a wide range of unsaturated aliphatic carbons,such as alkenes (including dienes, conjugated dienes, and trienes) andalkynes, which may contain a wide range of other functional groups. Forexample, using the present processes, it has been possible to achieveselective hydrogenation of the unsaturated carbon-carbon bond withoutsignificant reduction of e.g. carbonyl groups which may be present inthe substrate. Thus, the use of ionic liquids in the present processesprovides high, and at times very high, selectivities in such reactions.

[0039] A wide range of compounds containing at least one unsaturatedcarbon-carbon bond can be hydrogenated in accordance with the processesof the present invention. Suitable compounds that may be hydrogenatedinclude compounds containing at least one C═C bond. The process of thepresent invention is also readily applicable to the hydrogenation ofcompounds containing multiple C═C bonds, e.g. one to four C═C bonds,preferably one to three C═C bonds

[0040] The processes of the present invention can also be used tohydrogenate compounds containing at least one C≡C bond, as well ascompounds containing multiple C≡C bonds (e.g. up to two C≡C bonds).

[0041] The processes of the present invention can be readily applied tohydrogenate substrates having a wide molecular weight range. Forexample, suitable substrates include compounds containing from 2 to 50carbon atoms, preferably from 4 to 25 carbon atoms and more preferablyfrom 6 to 20 carbon atoms.

[0042] The hydrogenation process of the first aspect of the presentinvention may be used to hydrogenate both compounds containing only C═Cor C≡C functionalities, or compounds having a wide range of otherfunctional groups in addition to the unsaturated carbon-carbon bond tobe hydrogenated. In the latter case, it has been found that the presentprocess can be highly chemoselective, i.e. it is possible to achieveselective hydrogenation of e.g. the C═C or C≡C bonds only, withouthydrogenation of other functional groups.

[0043] For alkyne substrates, it is possible, by varying the catalystand ionic liquid, to achieve partial hydrogenation, e.g. of the C≡C bondto form a C═C bond. Further, by varying the catalyst and reactionconditions, complete hydrogenation to the alkane may be achieved.

[0044] The hydrogenation process of the present invention may be appliedto a wide range of compounds containing at least one unsaturatedcarbon-carbon bond, including alkenes, alkynes, esters, ethers,carboxylic acids, amines, amides, alcohols, fatty acids and estersthereof, steroids, prostaglandins, nitrites, aldehydes, ketones,isoprenoids, flavonoids, icosanoids, compounds containing a heterocyclicmoiety wherein the heteroatom(s) can be nitrogen or oxygen, andcompounds containing an aromatic moiety, such aryl-containing (e.g.phenyl-containing) compounds.

[0045] Preferred substrates include alkenes, alkynes, aldehydes, fattyacids and esters thereof, including those containing an α,β unsaturatedcarbonyl moiety.

[0046] Especially preferred carbonyl-containing compounds which aresuitable substrates for the hydrogenation process of the presentinvention include those having the formula:

[0047] wherein:

[0048] R¹ is selected from hydrogen or C₁ to C₂₀ straight chain orbranched alkyl or C₃ to C₈ cycloalkyl wherein said alkyl or cycloalkylgroup may be substituted with 1-3 substituents independently selectedfrom: C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁to C₂₀ alkyl and C₆ to C₁₀ aryl; or C₆ to C₁₀ aryl wherein said arylgroup may be substituted with 1-3 substituents independently selectedfrom C₁ to C₁₀ alkyl, hydroxyl, F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ whereinR⁴ is selected from H, C₁ to C₂₀ alkyl; and

[0049] R² represents C₁ to C₂₀ straight chain or branched alkenyl or C₅to C₈ cycloalkenyl wherein said alkenyl or cycloalkenyl group may besubstituted with 1-3 substituents independently selected from C₁ to C₂₀alkyl, C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁to C₂₀ alkyl and C₆ to C₁₀ aryl; or C₆ to C₁₀ aryl wherein said arylgroup may be substituted with 1-3 substituents independently selectedfrom C₁ to C₁₀ alkyl, hydroxyl, F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ whereinR⁴ is selected from H and C₁ to C₂₀ alkyl.

[0050] Preferably, in the above compounds:

[0051] R¹ is selected from hydrogen; C₁ to C₂₀ straight chain orbranched alkyl or C₃ to C₈ cycloalkyl wherein said alkyl or cycloalkylgroup may be substituted with 1-3 substituents independently selectedfrom: C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈cycloalkyl, hydroxyl, F, CF₃, ═O or OR³ wherein R³ is selected from H,C₁ to C₂₀ alkyl and C₆ to C₁₀ aryl; or C₆ to C₁₀ aryl; and

[0052] R² represents C₁ to C₂₀ straight chain or branched alkenyl or C₅to C₈ cycloalkenyl wherein said alkenyl or cycloalkenyl group may besubstituted with 1-3 substituents independently selected from C₁ to C₂₀alkyl, C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, hydroxyl, F, CF₃,═O or OR³ wherein R³ is selected from H, C₁ to C₂₀ alkyl and C₆ to C₁₀aryl; or C₆ to C₁₀ aryl.

[0053] Also preferred are compounds of the above formula wherein:

[0054] R¹ is selected from hydrogen; C₁ to C₁₀ straight chain orbranched alkyl; and

[0055] R² represents C₁ to C₂₀ straight chain or branched alkenyl or C₅to C₈ cycloalkenyl wherein said alkenyl or cycloalkenyl group may besubstituted with 1-3 substituents independently selected from C₁ to C₂₀alkyl or C₆ to C₁₀ aryl.

[0056] Especially preferred are those compounds wherein:

[0057] R¹ is selected from hydrogen; C₁ to C₁₀ straight chain orbranched alkyl; and

[0058] R² represents C₁ to C₂₀ straight chain or branched alkenyl or C₅to C₈ cycloalkenyl wherein said alkenyl or cycloalkenyl group may besubstituted with C₁ to C₁₀ alkyl or phenyl.

[0059] The hydrogenation process of the present invention isparticularly suitable for compounds as defined above wherein anα,β-unsaturated carbonyl moiety is present. In such compounds, it hasbeen found that the carbon-carbon double bond can be hydrogenatedselectively, i.e. the C═C bond can be hydrogenated in preference to theC═O bond.

[0060] Specific examples of suitable compounds include cinnamaldehyde,2-octenal, citral, methylvinylketone, 3-cyclohexene-1-carboxaldehyde andbenzylidine acetone.

[0061] Alkenes which may be hydrogenated using the present processinclude those having the formula:

[0062] wherein:

[0063] R⁵, R⁶, R⁷ and R⁸ may be the same or different and each isindependently selected from:

[0064] hydrogen;

[0065] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkylwherein said alkyl or cycloalkyl group may be substituted with 1-3substituents independently selected from: C₂ to C₁₀ alkenyl, C₅ to C₈cycloalkenyl, C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀alkaryl, C₃ to C₈cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁to C₂₀ alkyl and C₆ to C₁₀ aryl;

[0066] C₂ to C₂₀ straight chain or branched alkenyl;

[0067] C₅ to C₈ cycloalkenyl; or

[0068] C₆ to C₁₀ aryl wherein said aryl group may be substituted with1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl,F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H and C₁ toC₂₀ alkyl.

[0069] Preferably, R⁵, R⁶, R⁷ and R⁸ are the same or different and eachis independently selected from:

[0070] hydrogen;

[0071] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkylwherein said alkyl or cycloalkyl group may be substituted with 1-3substituents independently selected from: C₂ to C₁₀ alkenyl, C₅ to C₈cycloalkenyl, C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈cycloalkyl, hydroxyl, F, CF₃ or OR³ wherein R³ is selected from H, C₁ toC₂₀ alkyl and C₆ to C₁₀ aryl; and

[0072] C₂ to C₂₀ straight chain or branched alkenyl.

[0073] Also preferred are compounds wherein R⁵, R⁶, R⁷ and R⁸ are thesame or different and each is independently selected from:

[0074] hydrogen;

[0075] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈cycloalkyl; and

[0076] C₂ to C₂₀ straight chain or branched alkenyl.

[0077] Especially preferred are compounds wherein R⁵, R⁶, R⁷ and R⁸ arethe same or different and each is independently selected from hydrogen;C₁ to C₂₀ straight chain or branched alkyl; and C₂ to C₂₀ straight chainor branched alkenyl.

[0078] Particularly preferred are alkenes of the above formula whereinR⁵ and R⁷ each represents hydrogen.

[0079] Also preferred are alkenes of the above formula wherein R⁶ and R₈are each independently selected from C₁ to C₂₀ straight chain orbranched alkyl, C₃ to C₈ cycloalkyl and C₂ to C₂₀ straight chain orbranched alkenyl.

[0080] Preferred alkene substrates are those wherein R⁵, R⁶ and R⁷ eachrepresents hydrogen and R⁸ is as defined in any preceding passage.

[0081] Thus, the hydrogenation process of the present invention may beapplied to a wide range of alkenes including those having the formula

[0082] wherein R⁵, R⁶ and R⁷ are as defined in any of the precedingpassages.

[0083] Especially preferred alkene substrates include those as definedabove wherein R⁵, R⁶, R⁷ or R⁸ represents a C₂ to C₂₀ straight chain orbranched alkenyl.

[0084] The process of the present invention is also suitable for thehydrogenation of alkynes including those having the formula:

R⁹C≡CR¹⁰

[0085] wherein R⁹ and R¹⁰ are each independently selected from:

[0086] hydrogen;

[0087] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkylwherein said alkyl or cycloalkyl group may be substituted with 1-3substituents independently selected from: C₂ to C₁₀ alkenyl, C₅ to C₈cycloalkenyl, C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁to C₂₀ alkyl and C₆ to C₁₀ aryl; and

[0088] C₆ to C₁₀ aryl wherein said aryl group may be substituted with1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl,F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H and C₁ toC₂₀ alkyl.

[0089] Particularly suitable alkyne substrates are those wherein R⁹ andR¹⁰ are each independently selected from:

[0090] hydrogen;

[0091] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkylwherein said alkyl or cycloalkyl group may be substituted with 1-3substituents independently selected from: C₆ to C₁₀ aryl, C₈-C₂₀aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈ cycloalkyl, hydroxyl or OR³ wherein R³is selected from H, C₁ to C₂₀ alkyl and C₆ to C₁₀ aryl; and

[0092] C₆ to C₁₀ aryl wherein said aryl group may be substituted with1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl,F or OR⁴ wherein R⁴ is selected from H and C₁ to C₂₀ alkyl.

[0093] Especially preferred are compounds wherein R⁹ and R¹⁰ are eachindependently selected from:

[0094] hydrogen;

[0095] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈cycloalkyl; and

[0096] C₆ to C₁₀ aryl wherein said aryl group may be substituted with1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl,F or OR⁴ wherein R⁴ is selected from H and C₁ to C₂₀ alkyl.

[0097] Also preferred are compounds wherein R⁹ and R¹⁰ are eachindependently selected from:

[0098] hydrogen;

[0099] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈cycloalkyl; and

[0100] C₆ to C₁₀ aryl wherein said aryl group may be substituted with1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl,or OR⁴ wherein R⁴ is selected from H and C₁ to C₁₀ alkyl.

[0101] Alkynes of the above formula wherein R⁹ and R¹⁰ are each selectedfrom hydrogen, C₁ to C₁₀ alkyl which may be substituted by hydroxyl, orphenyl are particularly preferred.

[0102] Especially preferred alkynes of the above formula are thosewherein at least one of R⁹ or R¹⁰ is hydrogen.

[0103] For the hydro-dehalogenation process of the present invention,the substrate may be any compound having at least one C—Cl, C—Br or C—Ibond. Suitable substrates include those wherein the compound has theformula:

P-X

[0104] wherein:

[0105] P represents a group selected from:

[0106] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkylwherein said alkyl or cycloalkyl group may be substituted with 1-3substituents independently selected from: C₆ to C₁₀ aryl, C₈-C₂₀aralkyl, C₈-C₂₀alkaryl, C₃ to C₈ cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ toC₆ alkylamino, C₁ to Ce dialkylamino, —CN, COOR³, CONR³ or OR³ whereinR³ is selected from H, C₁ to C₂₀ alkyl and C₆ to C₁₀ aryl;

[0107] C₆ to C₁₀ aryl wherein said aryl group may be substituted with1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl,F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H and C₁ toC₂₀ alkyl:

[0108] heteroaryl; or

[0109] heterocycloalkyl; and

[0110] X represents Cl, Br or I

[0111] Of these compounds, those wherein P represents:

[0112] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkylwherein said alkyl or cycloalkyl group may be substituted with 1-3substituents independently selected from: C₆ to C₁₀ aryl, C₈-C₂₀aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈ cycloalkyl, hydroxyl;

[0113] C₆ to C₁₀ aryl wherein said aryl group may be substituted with1-3 substituents independently selected from C₁ to C₁₀ alkyl, orhydroxyl;

[0114] heteroaryl; or

[0115] heterocycloalkyl

[0116] are preferred.

[0117] Also preferred are those compounds wherein P represents:

[0118] C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈cycloalkyl;

[0119] C₆ to C₁₀ aryl wherein said aryl group may be substituted with1-3 substituents independently selected from C₁ to C₁₀ alkyl, orhydroxyl;

[0120] heteroaryl, wherein said heteroaryl group is a purine orpyrimidine; or

[0121] heterocycloalkyl.

[0122] The hydro-dehalogenation process of the present invention isparticularly suitable for compounds containing at least one C—Cl bond.

[0123] The present invention extends to any product obtainable by theprocesses herein described.

[0124] In the processes of the present invention, any suitableheterogeneous hydrogenation catalyst may be used. Particularly suitableare heterogeneous hydrogenation catalysts comprising nickel (e.g. Raneynickel), palladium, ruthenium, iridium, rhodium and platinum having anoxidation state of zero.

[0125] Especially preferred heterogeneous hydrogenation catalysts arethose comprising palladium or platinum.

[0126] The heterogeneous hydrogenation catalysts are preferably in theform of a finely divided metal.

[0127] Typically, the catalyst is supported on an inert support, such asactivated carbon, alumina, silica, silica-alumina, carbon black,graphite, titania, zirconia, calcium carbonate, and barium sulfate.

[0128] Preferred inert support materials are selected from activatedcarbon, carbon black, graphite, alumina or silica.

[0129] The hydrogenation catalysts for use in the present invention areheterogeneous, i.e. they do not dissolve in the ionic liquid, butinstead remain as a suspension therein. However, the catalyst ispreferably non-colloidal, i.e. the catalyst particle size, includingsupport (if any) is greater than 20, preferably greater than 50, andpreferably greater than 100 μm.

[0130] The processes of the present invention preferably employ ascatalyst, a platinum or palladium group metal, particularly in supportedform, e.g. on carbon, graphite or alumina.

[0131] The hydrogenating agent employed in the present process istypically molecular hydrogen or an organic or inorganic hydrogentransfer agent. Hydrogen transfer agents [see e.g. Johnstone et al.,Chem. Rev. (1985), 85, 129 and. Brieger et al. Chem. Rev. (1974), 74,567-580] are compounds which can release hydrogen and which arethemselves oxidised. An example of such a hydrogen transfer agent iscyclohexene, which undergoes the following reaction in the presence ofe.g. a palladium catalyst and an alkene substrate:

[0132] In such a process, the alkene is hydrogenated whilst thecyclohexene is oxidised to benzene.

[0133] Other suitable hydrogenating agents include molecular deuterium,HD, molecular tritium, HT, DT, or an organic or inorganic hydrogen,deuterium or tritium transfer agent.

[0134] Preferably, however, the hydrogenating agent is molecularhydrogen or an organic or inorganic hydrogen transfer agent. Molecularhydrogen is especially preferred as the hydrogenating agent.

[0135] The hydrogenation process of the present invention is preferablyconducted at temperatures of from 15° C. to 200° C., preferably 15° C.to 140° C., and more preferably from 20° C. to 100° C. Good results areobtained at temperatures of 40° C. to 60° C.

[0136] Where a non-gaseous hydrogenating agent is employed, the reactionmay be conducted at atmospheric pressure.

[0137] Where a gaseous hydrogenating agent such as molecular hydrogen isused, the reaction may be conducted at pressures of 101 kPa (i.e.atmospheric pressure) to 8 MPa. Typically, such reactions are conductedat pressures of from 150 kPa (preferably from 1 MPa) to 5 MPa and morepreferably from 2.5 MPa to 4.5 MPa. Good results may be obtained usingreaction pressures of 3 MPa to 4.2 MPa.

[0138] Hydrogenation reactions represent one of the largest uses ofheterogeneous catalysts in the chemical industry. A range of reactionsis possible from dehalogenation to simple reductions of alkene toselective reductions of α,β-unsaturated carbonyl containing molecules.Ionic liquids have not been used previously for any heterogeneouslycatalysed reactions and provide distinct advantages over manyconventional organic and aqueous solvents where selectivity may be poorand/or there are problems with product separation and recycle of thecatalyst/solvent system.

[0139] We believe we have found the first application of heterogeneouscatalysts in ionic liquids for hydrogenation reactions. After thehydrogenation reaction, the hydrogenation catalysts remain suspended inthe ionic liquid and are thus easily recyclable without the need toexpose the catalyst to air or filter the catalyst from the reactionmixture. This increases the safety of hydrogenation processes especiallywhere recycle of the catalyst is required. Ionic liquids also provide amedium where selectivity can be tuned for a given catalyst overconventional organic solvents.

[0140] Particular ionic liquids discussed herein include;

[0141] 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF₆),

[0142] 1-hexyl-3-methylimidazolium hexafluorophosphate (C₆mimPF₆),

[0143] 1-octyl-3-methylimidazolium hexafluorophosphate (C₈mimPF₆),

[0144] 1-decyl-3-methylimidazolium hexafluorophosphate (C₁₀mimPF₆),

[0145] 1-dodecyl-3-methylimidazolium hexafluorophosphate (C₁₂mimPF₆),

[0146] 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulphonyl)amide(emimNTf₂),

[0147] 1-hexyl-3-methylimidazolium bis((trifluoromethyl)sulphonyl)amide(C₆ mimNTf₂),

[0148] 1-hexylpyridinium tetrafluoroborate (C₆py BF₄),

[0149] 1-octylpyridinium tetrafluoroborate (C₈py BF₄),

[0150] 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF₄).

[0151] Unless indicated otherwise, the terms used herein have themeanings as indicated below:

[0152] “Alkyl” (including alkyl portions of alkyoxy, alkaryl, aralkyl,alkylamino, dialkylamino) represents straight and branched carbon chainscontaining from 1 to 40 carbon atoms, preferably 1 to 40 carbon atoms,and more preferably 4 to 12 carbon atoms.

[0153] “Cycloalkyl” represents saturated carbocyclic rings branched orunbranched containing from 3 to 20 carbon atoms, preferably 3 to 8carbon atoms. Such cycloalkyl groups include cyclopentyl and cyclohexyl.

[0154] “Heterocycloalkyl” represents a saturated, branched or unbranchedcarbocyclic ring containing from 3 to 12 carbon atoms, preferably from 4to 6 carbon atoms, wherein the carbocyclic ring is interrupted by 1 to 3heteroatom moieties selected from —O—, or —N(C₁ to C₆ alkyl), or NH.Such heterocycloalkyl groups include 2- or 3-tetrahydrofuranyl, 2-, 3-or 4-piperidinyl, 2-, 3- or 4-piperizinyl, morpholinyl, 2- or3-pyrrolidinyl and 2- or 4-dioxanyl.

[0155] “Alkenyl” represents straight and branched carbon chains havingat least one carbon to carbon double bond and containing from 2 to 40carbon atoms, preferably 2 to 20 carbon atoms and more preferably from 2to 12 carbon atoms. Thus, the term “alkenyl” as used herein includesdienes (including conjugated dienes) trienes and tetraenes.

[0156] “Cycloalkenyl” represents saturated carbocyclic rings branched orunbranched containing from 3 to 20 carbon atoms, preferably 3 to 8carbon atoms, wherein the ring contains at least one C═C bond.Cyclohexenyl and cyclopentenyl are particularly preferred cycloalkenylgroups.

[0157] “Alkynyl” represents straight and branched carbon chains havingat least one carbon to carbon triple bond and containing from 2 to 20carbon atoms, preferably 2 to 20 carbon atoms and more preferably from 2to 12 carbon atoms.

[0158] “Aryl” including aryl moieties in e.g. aralkyl represents acarbocyclic group containing from 6 to 15 carbon atoms (preferably from6 to 10 carbon atoms) and having at least one aromatic ring, with allavailable substitutable carbon atoms of the carbocyclic group beingintended as possible points of attachment. Preferred aryl groups includephenyl and naphthyl. Unless otherwise indicated, the term “aryl”includes such carbocyclic groups being optionally substituted with, 1 to3 of the following substituents: C₁ to C₆ alkyl, OH, O(C₁ to C₆ alkyl),phenoxy, CF₃, (C₁ to C₆ alkyl)amino, di(C₁ to C₆ alkyl)amino, —COO(C₁ toC₆ alkyl) or NO₂.

[0159] “Heteroaryl” represents cyclic groups having at least oneheteroatom selected from —O— or —N—, said heteroatom interrupting acarbocyclic ring structure and having a sufficient number of delocalisedpi electrons to provide aromatic character, with the aromaticheterocyclic groups preferably containing from 2 to 14 carbon atoms.Suitable heteroaryl groups include pyridine, indole, imidazole,pyridazine, pyrazine, oxazole, triazole, pyrazole, and purines andpyrimidines.

[0160] The present invention will be discussed in more detail by way ofthe following examples and figures:

[0161]FIG. 1a: Variation in product distribution with time followingcinnamaldehyde 1 reduction over 5 wt % Pt/graphite catalyst in bmimPF₆.

[0162]FIG. 1b: Variation in conversion and selectivity towards 2 withtime following cinnamaldehyde reduction over 5 wt % Pt/graphite catalystin bmimPF₆.

[0163]FIG. 2a: Variation in product distribution with time followingcinnamaldehyde 1 reduction over 5 wt % Pt/AI₂O₃ catalyst in bmimPFe.

[0164]FIG. 2b: Variation in conversion and selectivity towards 2 withtime following cinnamaldehyde reduction over 5 wt % Pt/Al₂O₃ catalyst inbmimPF₆.

[0165]FIG. 3a: Variation in product distribution with time followingcinnamaldehyde 1 reduction over 5 wt % Pt/graphite catalyst inpropan-2-ol.

[0166]FIG. 3b: Variation in conversion and selectivity towards 2 withtime following cinnamaldehyde reduction over 5 wt % Pt/graphite catalystin propan-2-ol.

[0167]FIG. 4: Variation in conversion and selectivity towards 2 withionic liquid volume following cinnamaldehyde reduction over 5 wt %Pt/graphite catalyst in emimNTf₂.

[0168]FIG. 5: Variation in conversion and selectivity towards 2 withtemperature following cinnamaldehyde reduction over 5 wt % Pt/graphitecatalyst in emimNTf₂.

[0169]FIG. 6: Variation in conversion of 1 to 3 with pressure followingcinnamaldehyde reduction over 10 wt % Pd/C catalyst in bmimBF₄.

[0170]FIG. 7: Kinetic study for the conversion (conv) andchemoselectivity (cs) in the hydrogenation of citral to citronellal in10 wt % Pd/C and 10 wt % Pd/C modified catalysts in bmimBF₄

[0171]FIG. 8: Variation in conversion of 1-nonyne and selectivitytowards 1-nonene with time following 1-nonyne reduction over 10 wt %Pd/C catalyst in C₆PyBF₄ at 30° C. and 3×10⁵ Pa.

[0172]FIG. 9a: Variation in conversion and selectivity towards styrenewith pressure following phenyl acetylene reduction over 5 wt % Pd/CaCO3at 30° C. after 4 hr.

[0173]FIG. 9b: Variation in conversion and selectivity towards styrenewith temperature following phenyl acetylene reduction over 5 wt %Pd/CaCO₃ at 3×10⁵ Pa for 4 hr.

[0174]FIG. 9c: Variation in conversion and selectivity towards styrenewith time following phenyl acetylene reduction over Pd/CaCO₃ at 3×10⁵ Pa& 30° C.

EXAMPLES

[0175] In the examples hereinafter, all reactions were carried out in aBaskerville mini autoclave. For all results, the selectivity is definedas follows:${\% \quad {selectivity}\quad n} = {\frac{\% \quad n}{{Sum}\quad {of}\quad {the}\quad \% \quad {products}\quad {formed}} \times 100}$

[0176] where % n is the percentage yield of n.

[0177] The ionic liquids for use in the present invention includingthose employed in the following examples can be made by process such asthose disclosed in WO 01/40146.

Example 1

[0178] 1.0 Hydrogenation of Cinnamaldehyde Using Platinum BasedCatalysts

[0179] Cinnamaldehyde, 1, can undergo reduction using hydrogen gas overa heterogeneous catalyst to produce three products, cinnamylalcohol, 2,hydrocinnamaldehyde, 3, and 3-phenylpropanol, 4. The reactions mayproceed in two different pathways 1 to 2 to 4 or 1 to 3 to 4 as shownbelow. This reaction has been studied extensively by many workers withan aim to control the selectivity and promote the formation ofcinnamylalcohol and hydrocinnamaldehyde without further reduction to3-phenylpropanol. These investigations have concentrated on the effectof promoters on the catalyst such as doping with tin or using zeolitebased catalysts. The aim of this study was to develop ionic liquids forheterogeneously catalysed reactions and specifically in this case toinvestigate whether the solvent could act as a promoter without the needto use expensive catalysts.

[0180] Each system was compared with propan-2-ol as a benchmark solvent.In the best cases, recycle of the catalyst was attempted. This researchshows the potential of ionic liquids to promote selectivity inheterogeneously catalysed reactions with the ability to recycle thecatalyst without the need to reactivate it. Some mechanistic detailshave also been studied and show that isomerisation between 2 and 3dominates the overall selectivity of the reduction rather than secondaryreduction processes.

[0181] Unless otherwise stated the reactions were performed under ahydrogen pressure of 4 MPa and a temperature of 60° C. The platinumcatalysts were pre-reduced in flowing hydrogen at 350° C. for 1 h. Ionicliquid (2 ml), 17.5 mg (5 wt % Pt catalyst), and cinnamaldehyde 0.5 ml(substrate/metal ˜800/1) were introduced to the autoclave and purgedthree times with argon. Hydrogen at 4 MPa was introduced and theautoclave heated to the required temperature. The reaction is left tostir for 6 h, upon which the reaction is cooled and the pressurereleased.

[0182] The reaction products were extracted using diethyl ether (2×10ml), which removes all the organic products whilst maintaining thecatalyst in the ionic liquid. Product selectivities and conversions weredetermined using GC-FID.

[0183] Table 1 summarises the results of an initial screening for thehydrogenation of cinnamaldehyde using 5% Pt/graphite in a range of ionicliquids. TABLE 1 Cinnamaldehyde hydrogenation^(a) variation with ionicliquid type using 5% Pt/graphite catalyst. Solvent % Conversion %Selectivity 2 emimNTf₂ 85 81 C₆mimNTf₂ 72 83 C₆mimPF₆ 50 46 bmimBF₄  776 bmimPF₆ ^(a) 47 83 bmimPF₆ ^(b) 49 81 bmimPF_(6c) 60 81propan-2-ol^(d) 89 53

[0184] These results suggest that the hydrogenation of cinnamaldehyde isinhibited in [BF₄]⁻ ionic liquids and that [NTf₂]⁻ based systems aremore active than those containing [PF₆]⁻. Although the conversions forthe ionic liquid systems were lower in comparison with propan-2-ol,higher selectivity was maintained at high conversion. It should be notedthat in all the ionic liquid reactions, the yield of 4 was negligiblewhereas in the propan-2-ol reactions this formed the majority of productat 100% conversion. Other anions tested included nitrate, sulfate,hydrogensulphate, hydrogencarbonate, acetate, trifluoroacetate and(S)-lactate; these resulted in little or no conversion. ReplacingPt/graphite with Pt/alumina resulted in lower selectivities andconversions in general.

[0185] The addition of trace amounts of nitric acid increased the yieldfrom 47 to 60% without any significant effect on selectivity. It is notclear as yet whether the acid changes the nature of the catalyst surfaceor influences the redox chemistry of the reaction. The addition of acidis detrimental to the workup, however, since it increases the ionicliquid solubility in common organic solvents, which results in leachingof both the catalyst and the ionic liquid into the organic phase duringextraction.

[0186] A number of reductions were also carried out in pyridinium andammonium ionic liquids with little success. Pyridinium and ammonium BF₄and bistriflimides liquids showed no reaction as was the case forpyrollidinium and piperidinium bistriflimides. It is also worth notingthat all of the ‘solid’ solvents employed (for example pyridinium PF6systems) gave no reaction despite melting below the reaction temperatureof 60° C.

[0187] From the initial screening, imidazolium ionic liquids achieve thehighest yields and selectivity with the trend [NTf₂]⁻>[PF₆]⁻>[BF₄]⁻. Thebest system, emimNTf₂, is hydrophobic enabling chloride removalefficient simply by washing with water. It has very low viscosity, whichmakes it easy to handle and allow for catalyst dispersion.

[0188] 1.1 Kinetic Study on the Hydrogenation of Cinnamaldehyde

[0189] Two kinetic studies were carried out to compare the effect ofcatalyst support. FIGS. 1a, 1 b, 2 a and 2 b show the hydrogenation ofcinnamaldehyde using Pt/graphite or Pt/alumina in bmimPF₆. In bothcases, the reaction stops after 5-7 hrs with the conversion rate slowingsignificantly after 3-5 hrs. Initially the selectivity is high towardscinnamylalcohol 2 however, with increasing reaction time somehydrocinnamaldehyde 3 and 3-phenylpropanol 4 forms. We believe that theformation of 3 occurs because of isomerisation between 2 and 3 catalysedby the supported catalyst in the ionic liquid. This is more pronouncedin the case of Pt/Al₂O₃ catalysts where a maximum in the selectivity isclearly observed. In both reactions only trace (<2%) of the totallysaturated product, 4, is formed. Separate experiments studying theisomerisation of cinnamylalcohol in the presence of Pt catalysts in arange of ionic liquids under an inert atmosphere at 60° C. gave up to60% isomerisation to hydrocinnamaldehyde after 4 hrs. (Note the blankreactions and those performed in propan-2-ol gave negligibleconversion). In agreement with the hydrogenation experiments Pt/aluminais more effective than Pt/graphite for the isomerisation.

[0190] These kinetic runs may be compared with a similar study usingPt/graphite in propan-2-ol performed at 60° C., shown in FIGS. 3a and 3b. More conversion is found in propan-2-ol, however, the selectivitytowards 2 is poor above 75% conversion. At lower temperatures theselectivity and conversion are both poor.

[0191] Catalyst deactivation is likely to be the cause of the conversionbeing limited. To assess whether the substrate or ionic liquid wascausing the deactivation, a blank experiment in which the hydrogenationwas carried out under normal experimental conditions for 6 hrs withoutany substrate, cooled, the substrate was added and the reactionperformed once more. Under these conditions, no reaction was observedindicating that the ionic liquid, and not the substrate/products, wasresponsible for the catalyst poisoning.

[0192] Poisoning by the ionic liquid could be the result of a number ofvariables, for example pore blocking, the blocking sites by stronglyadsorbed species or halide contamination from the ionic liquidmanufacture. Experiments were performed in the presence of trace halidefrom HCl and NaCl to assess the contribution of halide deactivation. Noconversion was observed in these reactions showing that firstly theionic liquids are used were virtually halide free and secondly, absenceof halide impurities is important if these reactions are to proceed. Themajor consequence of this is that unless electrolysis is performed priorto use, these reactions are limited to hydrophobic ionic liquids, whichmay be washed with water to remove trace chloride.

[0193] Deactivation via strongly adsorbed species was investigated byvarying the ionic liquid to catalyst/substrate ratio. The results ofthis study are shown in FIG. 4.

[0194] Varying the volume of ionic liquid used resulted in littlevariation in selectivity; however, the conversion was found to varystrongly. Significantly, a maximum in conversion is observed. Thisoccurs at smaller ionic liquid volumes than had been used previously.

[0195] 1.2 Recycle

[0196] The initial screening results (Table 1) showed that although itwas possible to recycle the ionic liquid, however, in general recycle ofthe ionic liquid/platinum catalyst resulted in little reaction. Usingthe optimum conditions found from FIG. 4, recycle of the catalyst andionic liquid was possible. The ionic liquid was simply extracted withoutremoving the catalyst resulting in 99% of the starting material andproducts being removed, and fresh cinnamaldehyde added. Using thissystem, 42% conversion and 80% selectivity was achieved after 6 hourscompared with 85% conversion and 81% selectivity for the fresh catalystsystem. It should be noted that, extraction results in little transferof catalyst to the extracting phase and on recycle the catalyst was notpre-activated in hydrogen. As described in the experimental, the normalprocedure for the reaction with platinum catalysts is to activate thecatalyst in flowing hydrogen at temperature prior to reaction. Withoutthis procedure little reaction occurs and the fact that recycle ispossible without further activation shows a significant benefit of usingionic liquids as solvents over conventional organic solvent Osystems.

[0197] 1.3 Temperature Study on the Effect of Conversion/Selectivity

[0198] Optimisation with respect to temperature was also performed andthe results are shown in FIG. 5.

[0199] Selectivity and conversion map each other with a maximum in bothat 60° C. The selectivity maximum presumably indicates a balance betweenadsorption and isomerisation. At low temperatures, desorption is low andhence secondary reactions occur whereas at higher temperatureisomerisation from 2 to 3 is favoured. Two competing effects may alsocause the maximum in conversion, reaction rate and hydrogen solubility.The former rises with temperature whereas the latter drops. Above 90° C.significant polymerisation occurred.

[0200] 1.4 Hydrogenation of Cinnamaldehyde in C_(n)-MethylimidazoliumIonic Liquids

[0201] A study into the effect of increasing alkyl chain length (C₄-C₁₂)in the imidazolium systems is summarized in Table 2. This demonstratesthat there is no advantage in the use of higher chain ionic liquidssince, although the selectivity remains constant, the yield decreasessteadily as chain length increases. One would expect that increasing thechain length would result in increased hydrogen solubility in the ionicliquid and this might, in turn, increase the conversion rate as the sidechain lengthened. However, as the side chain lengthens, the ionic liquidbecomes more viscous and mass transfer effects dominate the reaction,reducing the rate. TABLE 2 Variation in hydrogenation of 1 using 5%Pt/graphite with increasing alkyl chain length in [C_(n)mim]+ ionicliquids. Solvent % Conversion % Selectivity 2 bmimPF₆ 43 84 C₆mimPF₆ 4685 C₈mimPF₆ 35 83 C₁₀mimPF₆ 13 81 *C₁₂mimPF₆ 0 0

[0202] 1.5 Hydrogenation of Different Substrates in C₆mim NTf₂ with 5 wt% Pt/G

[0203] A variety of different unsaturated aldehydes were reduced, so asto demonstrate that hydrogenations in ionic liquids are not restrictedto the compounds reduced thus far.

[0204] The results for the reduction of four different compounds with 5wt % Pt/G in C₆mim NTf₂ ionic liquid are shown in table 3. TABLE 3 Thereduction of four different substrates at 60° C. and 4 MPa after fourhours with 5 wt % Pt/G in C₆mim NTf₂. Substrate Product(s) Amount

100%

100%

 20%  56%

 20%  <1%

[0205] The results shown in Table 3 demonstrate that in the case of thesubstrates trans-2-octenal and methyl vinyl ketone, there was 100%formation of the fully saturated alcohol. For3-cyclohexene-1-carboxaldehyde, 20% of the product was saturatedaldehyde and for the reduction of benzylideneacetone the selectivity wasfound to be greater than 90% towards the alcohol product. It is worthnoting that these reactions have not been optimised and therefore do notrepresent either the optimum in selectivity or activity in this or anyother ionic liquid.

Example 2

[0206] 2.0 Hydrogenation of Cinnamaldehyde in Ionic Liquids Using 10%Pd/activated carbon

[0207] Palladium metal is known to reduce double bonds in preference tocarbonyl groups, however, in α,β-unsaturated systems there is little orno selectivity in common organic solvents. Cinnamaldehyde hydrogenationcarried out in propan-2-ol using Pd/activated carbon yielded the fullysaturated compound, 3-phenylpropanol, 4.

[0208] Unless otherwise stated the reactions were performed under ahydrogen pressure of 4 MPa and a temperature of 60° C. The palladiumcatalysts were used as received. Ionic liquid (2 ml), 5.5 mg (10 wt % Pdcatalyst), and cinnamaldehyde 0.5 ml (substrate/metal˜800/1) wereintroduced to the autoclave and purged three times with argon. Hydrogenat 40×10⁵ Pa was introduced and the autoclave heated to the requiredtemperature. The reaction is left to stir for 6 h, upon which thereaction is cooled and the pressure released.

[0209] The reaction products were extracted using diethyl ether (2×10ml), which removes all the organic products whilst maintaining thecatalyst in the ionic liquid. Product selectivities and conversions weredetermined using GC-FID.

[0210] Table 4 summarizes the results from reduction of cinnamaldehydeusing Pd/C in a range of ionic liquids. TABLE 4 Cinnamaldehydehydrogenation variation with ionic liquid type using 10% wt Pd/activatedcarbon Ionic liquid % 1 % 3 % 4 bmimPF₆ 0 100 0 bmimBF₄ 0 100 0C₆mimNTf₂ 0 46 54 emimNTf₂ 0 38 62 C₆pyBF₄ 23 77 0 C₈pyBF₄ 42 46 12propan-2-ol 0 0 100

[0211] It is clear from the table that the ionic liquid can adjust theselectivity towards hydrocinnamaldehyde, 3. Unlike in the case ofplatinum catalysts, all ionic liquid systems were found to be active,[PF₆]⁻ and [BF₄]⁻ systems gave high selectivity towards 3, in general,whereas [NTf₂]⁻ gave a mixture of products. Under no conditions wascinnamyl alcohol produced using Pd/C.

[0212] 2.1 Recycle.

[0213] Recycle of the palladium catalyst/ionic liquid was possible butas with the platinum case a reduction in conversion was observed onreuse. For example, recycle of Pd/C in bmimBF₄ showed 100% selectivitywith conversion of 17%. Similar selectivities and conversions wereobserved for the 2nd, 3rd, 4th, 5th and 6th recycles. We believe thatpore blocking may be the cause of the deactivation, at least in the caseof activated carbon catalysts. Washing the catalyst with acetonitrile,prior to recycle after a first run had little effect on the conversionachieved. Increasing the catalyst loading from 800/1-100/1 increased theinitial rate and all recycle (up to 5 recycles performed) showed 100%conversion and selectivity after 4 h to hydrocinnamaldehyde 3.

[0214] 2.2 Effect of Pressure on Reaction Rates

[0215]FIG. 6 shows the variation of conversion after 4 h with hydrogenpressure. The pressure study showed that, even at low pressures such as5×10⁵ Pa there was significant conversion, after 4 h of the reaction.After 24 h, 93% conversion to hydrocinnamaldehyde 3 at 5×10⁵ Pa wasobserved. At all pressures, only hydrocinnamaldehyde is found.

[0216] 2.3 Temperature Study on the Effect of Conversion/Selectivity

[0217] The conversion of cinnamaldehyde increases with increasingtemperature up to 60° C., whilst maintaining 100% selectivity tohydrocinnamaldehyde. Above 60° C., the selectivity decreases due to thehydrogenation of the carbonyl group, resulting in the formation of thefully saturated alcohol 4. There was no evidence for the formation of 4,when these reactions are run under standard conditions as described inthe experimental procedure, even after prolonged reaction time (24 h).TABLE 5 Cinnamaldehyde hydrogenation variation with temperature using10% Pd/activated carbon. Temp (° C.) % 1 % 3 % 4 % selectivity 3 30 7030 0 100 45 55 45 0 100 60 6 94 0 100 75 4 96 20 78 90 1 55 44 56

Example 3

[0218] 3.0 Palladium Catalysed Hydrogenation of Methyl Oleate

[0219] The palladium catalysts were used as received. Ionic liquid (2ml), 5.5 mg (10 wt % Pd catalyst), and methyl oleate 0.5 ml(substrate/metal˜800/1) were introduced to the autoclave and purgedthree times with argon. Hydrogen at 1 MPa was introduced and theautoclave heated to the required temperature. The reaction is left tostir for 4 h, upon which the reaction is cooled and the pressurereleased.

[0220] The reaction products were extracted using diethyl ether (2×10ml), which removes all the organic products whilst maintaining thecatalyst in the ionic liquid. Product selectivities and conversions weredetermined using GC-FID.

[0221] Methyl oleate 9 was hydrogenated to methyl stearate 10 with 100%conversion and selectivity after 4 h reaction at 60° C. in C₆pyBF₄,bmimPF₆ and emimNTf₂ ionic liquids. Following extraction the reactionwas recycled and achieved the same conversions and selectivity. Nocleavage of the ester group was observed and there was no loss of thecatalyst to the extractant phase.

[0222] The so-formed product, 10, remains in the upper layer of thereaction mixture, i.e. above the ionic-liquid phase. Consequently, theproduct can be readily isolated by decantation, thus avoiding the needfor extraction procedures. Thus, the use of ionic liquids in thehydrogenation of fatty acid esters may permit operation on a large scaleby a continuous process. Additionally, it is noted that thehydrogenation reactions may be carried out in relatively smallquantities of ionic liquid.

Example 4

[0223] 4.0 Palladium Catalysed Hydrogenation of Citral

[0224] The palladium catalysts were used as received. Ionic liquid (2ml), 5.5 mg (10 wt % Pd/C), and citral 0.5 ml (substrate/metal˜800/1)were introduced to the autoclave and purged three times with argon.Hydrogen at 4 MPa was introduced and the autoclave heated to therequired temperature. The reaction is left to stir for 6 h, upon whichthe reaction is cooled and the pressure released.

[0225] The reaction products were extracted using diethyl ether (2×10ml), which removes all the organic products whilst maintaining thecatalyst in the ionic liquid. Product selectivities and conversions weredetermined using GC-FID.

[0226] Citral has three sites of hydrogenation; the conjugate doublebond, the carbonyl group and the isolated double bond. The hydrogenationof citral 11, a compound with a ‘methyl blocking group’, proceeded withselective hydrogenation of the double bond to produce citronellal 13.Literature reports had suggested that the selectivity in traditionalsolvents was governed by temperature.

TABLE 6 Citral hydrogenation variation with ionic liquid type using 10wt % Pd/C catalyst. Solvent % Conversion % Selectivity 2 emimNTf₂ 85 83C₆mimNTf₂ 92 82 C₆mimPF₆ 72 96 bmimBF₄ 75 100 C₈PyBF₄ 56 100 Propan-2-ol100 41

[0227] From Table 6, the results suggest that generally the [BF_(4]) ⁻and the [PF₆]⁻ ionic liquids are more selective than the [NTf₂]⁻,however all ionic liquids tested are much more selective thanpropan-2-ol.

[0228] The temperature study produced conversion and selectivitiesanalogous to those obtained using cinnamaldehyde 1 as the substrate.From 30° C.-60° C., the conversion increases whilst maintaining highselectivity. Above 60° C. the formation of the alcohol, citronellol 14,leads to a decrease in selectivity. The citral used for the experimentcontains ˜65% (E), 35%(Z) isomers. However, it is interesting to observethat the ratio of E/Z isomers of the unreacted citral in theseexperiments was still 65/35 indicating that the catalytic system did notdiscriminate between the isomers, even though ft was only selective forthe reduction of the conjugated double bond. Even at high temperaturesand pressures, were citronellol 14 was formed there was no evidence forthe formation of the completely hydrogenated product 3,7-dimethyloctan-1-ol 15 or geraniol/nerol 12. TABLE 7 Pd/C catalysed hydrogenationof citral at various temperatures in bmimBF₄ Temp E/Z ratio of (° C.) %11 % 13 % 14 unreacted 11 30 58 42 0 61/39 45 40 60 0 66/34 60 27 73 062/38 75 8 92 0 61/39 90 0 53 47 0

[0229] 4.1 Modification of Heterogeneous Catalysts with Amino Acids

[0230] A series of palladium catalysts loaded onto to activated carbon,alumina and titania modified with (S)-proline (pro), (S)-phenylalanine(phal) and (S)-2-aminobutyric acid (aba) along with the alkaloidcinchonidine (cinc) were studied in the hydrogenation of citral.

[0231] Initial studies (Table 8) were carried out at 30° C. and 1 MPa onthe palladium catalysts modified with proline according to the followingprocedure. The chiral modifier (0.01 mmol) was added to a suspension ofionic liquid 2 ml containing the palladium catalyst. The mixture wasstirred for 1 h at 30° C. under 1 MPa of hydrogen to modify the catalystsurface before addition of the substrate molecule (0.52 m[of citral).The reaction was then re-pressurised to 1 MPa of H₂ and left to stir for5 h, upon which the pressure is released.

[0232] The reaction products were extracted using organic solvent ordistillation, which removes all the organic products whilst maintainingthe catalyst in the ionic liquid. Product selectivities and conversionswere determined using GC-FID. TABLE 8 Heterogeneous hydrogenation¹ ofcitral over modified Pd Chemo- Conversion/ Catalyst Modifier Solventselectivity/% % 10 wt % Pd/C pro Propan-2-ol 33 89 10 wt % Pd/C procyclohexane 57 85 10 wt % Pd/C pro bmimBF₄ 88 73 10 wt % Pd/C² probmimBF₄ 80 4  5 wt % pro bmimBF₄ 100 49 Pd/Al₂O₃  5 wt % pro bmimBF₄ 10027 Pd/Al₂O₃ ²  5 wt % Pd/TiO₂ pro bmimBF₄ 100 31  5 wt % Pd/TiO₂ ² probmimBF₄ 100 15  5 wt % Pd/TiO₂ cinc bmimBF₄ 100 25  5 wt % Pd/TiO₂ ababmimBF₄ 100 18  5 wt % Pd/TiO₂ phal bmimBF₄ 100 7

[0233] These results showed that citral is hydrogenated with excellentchemoselectivities in ionic liquid (Table 8). Furthermore, all of thecatalysts give much higher chemoselectivities when employed in ionicliquid compared with propan-2-ol and cyclohexane.

[0234] An attempted recycle of the 10 wt % Pd/C/ bmimBF₄ system resultedin very poor conversion (4%) and a drop in chemoselectivity from 88% to80%. Similar recycles of 5 wt % Pd/Al₂O₃ and 5 wt % Pd/TiO₂ in bmimBF₄gave similar chemoselectivities as the initial run but the conversionsdecreased. The use of other chiral modifiers, such as phenylalanine,2-aminobutyric acid and cinchonidine with 5 wt % Pd/TiO₂ in bmimBF₄showed no advantage over the proline based system.

[0235] A kinetic study of the conversion and chemoselectivity of a 10 wt% Pd/C modified catalyst (proline) versus an unmodified catalyst showsthat the reaction is faster in the modified system but thechemoselectivity drops with time (FIG. 7). The unmodified catalystmaintains 100% chemoselectivity throughout the reaction. The decrease inchemoselectivity observed with the modified catalyst is due to the overhydrogenation to citronellol.

[0236] Table 9 highlights the use of proline as a modifier on thereaction. (R)-proline, the unnatural enantiomer, as a chiral modifieragain produces similar conversion and to chemoselectivity as the natural(S)-enantiomer. The use of cironellal as a promoter/modifier on recyclewas not observed to increase chemoselectivity or conversion. Addition offresh amounts of proline as well as the use of a proline saturatedsystem shows excellent chemoselectivity and conversion on recycle. TABLE9 Effect of modifiers on catalyst recyclability Catalyst Modifier Chemo-Enantio- (5.5 mg) (0.01 mmol) selectivity/% selectivity Conversion/%Pd/C pro 100 0 78 Pd/C¹ pro + pro² 100 0 56 Pd/C sat. pro⁵ 100 0 73Pd/C¹ sat. pro 100 0 55 Pd/C pro 98 0 42 Pd/C¹ pro + cit³ 98 0 42 Pd/C⁴pro 86 0 100 Pd/C (R)-pro⁶ 96 0 73

[0237] Table 10 shows the effect of a proline saturated ionic liquid onthe recycle of 10 wt % Pd/C catalyst. The modified catalyst greatlyincreases the conversion upon the initial run and successive recycleswhile still maintaining 100% selectivity. Although the unmodifiedcatalyst also shows 100% selectivity over the three recycles performed,the conversions upon recycle are much lower than modified catalyst.TABLE 10 Catalyst recycle for 10 wt % Pd/C modified (sat. Proline)hydrogenation in bmim BF₄. 10% Pd/C unmodified 10% Pd/C modified Run %conversion % selectivity % conversion % selectivity 1 42 100 79 100 2 16100 42 100 3 17 100 41 100 4 16 100 43 100

[0238] If a salt of proline is used, such a salt may remain suspended inthe ionic liquid. Thus, separation of the product can easily be carriedout by extraction procedures.

Example 5

[0239] Heterogeneously Catalysed Dehalogenation of 6-Chloropurine.

[0240] The palladium on carbon catalysts were used as received usedwhereas the platinum catalysts and palladium on alumina were pre-reducedin flowing hydrogen at 350° C. for 1 h. Ionic liquid (2 ml), 5.5 mg (10wt % Pd on carbon), 11 mg (5 wt % palladium on alumina), 19.5 mg (5 wt %platinum on alumina), 19.5 mg (5 wt % platinum on graphite), andsubstrate (substrate/metal ˜200/1) were introduced to the autoclave andpurged three times with argon. Hydrogen at the desired pressure wasintroduced and the autoclave heated to the required temperature. Thereaction is left to stir for the desired time period, upon which thereaction is cooled and the pressure released. The reaction products areextractable using water.

[0241] The reaction conversion and selectivity was analysed by HPLC.

[0242] Table 11 shows the conversion and selectivity for the reaction to16 over 17. TABLE 11 Hydro-dehalogenation of 6-chloropurine^(c) in bmimBF₄/PF₆ % Conversion^(a) Catalyst Ionic liquid^(b) Pressure Temperature(Selectivity)^(a) 5 wt % Pt/G bmimPF₆ 10 60  59 (100) 5 wt % Pt/GbmimPF₆ 40 60  82 (100) 5 wt % Pt/Al₂O₃ bmimBF₄ 40 60 100 (83)  5 wt %Pt/Al₂O₃ bmimPF₆ 40 60 100 (69)  5 wt % Pd/Al₂O₃ bmimBF₄ 40 60  87 (100)5 wt % Pd/Al₂O₃ bmimBF₄ 10 60 76 (96) 5 wt % Pd/Al₂O₃ bmimPF₆ 10 60 66(92) 5 wt % Pd/CaCO₃ bmimBF₄ 40 60 62 (98) 5 wt % Pd/CaCO₃ bmimBF₄ 10 6039 (99)

[0243] Pressure had little effect on selectivity for the platinum orpalladium systems but lower pressure seemed to result in lowerconversions. All of the catalysts used showed good conversion and goodselectivity in the ionic liquids studied. TABLE 12 Catalyst recycle fordechlorinations of 6-chloropurine in BmimBF₄ 5% Pd/Al₂O₃ 5% Pd/CaCO₃ Run% conversion % selectivity % conversion % selectivity 1 94 100 67 100 238 98 62 95 3 30 97 60 99 4 23 99 51 100

[0244] Recycle of Pd/Al₂O₃ and Pd/CaCO₃ systems was conducted at 60° C.and 4 MPa of hydrogen S/C 200/1. Catalyst deactivation is thought to bea common problem through poisoning by HX, sintering or coking. Sinteringof the catalyst is not thought to be an issue, as this has only beenreported to occur in gas phase reactions. Table 12 shows that catalystdeactivation in ionic liquids is possibly due to hydrogen halideformation which is eliminated by the use of a basic support. The slightdecrease in activity over the recycles may be due to coking.

[0245] The dehalogenation of a range of mono-substituted benzenes andsubstituted halofluorobenzenes is shown in Table 13. From Table 13 theselective dehalogenation of a range of substituted fluorobenzenesproceeds very smoothly producing only fluorobenzene. There is nospectral evidence for the defluorination to benzene or arenehydrogenation. Chlorobenzene proved to be more difficult to dehalogenatethan bromobenzene but went to completion after 24 h, when CaCO₃ was usedas the support. It has been well documented that side reactions such asdimerisation and hydroisomerisation can occur during the dehalogenationof chlorobenzene, although this has not been observed in our systems.TABLE 13 Hydrogenation^(a) of substituted benzenes in bmimBF₄ CatalystSubstrate Conversion^(b) 5 wt % Pd/CaCO₃ 4-Cl-fluorobenzene 100%^(c) 5wt % Pd/Al₂O₃ 4-Cl-fluorobenzene 100%^(c) 5 wt % Pd/CaCO₃3-Cl-fluorobenzene 100%^(c) 5 wt % Pd/CaCO₃ 2-Cl-fluorobenzene 100%^(c)5 wt % Pd/CaCO₃ 4-Br-fluorobenzene 100%^(c) 5 wt % Pd/CaCO₃3-Br-fluorobenzene 100%^(c) 5 wt % Pd/CaCO₃ 4-I-fluorobenzene 100%^(c) 5wt % Pd/Al₂O₃ chlorobenzene  2%^(d) 5 wt % Pd/CaCO₃ chlorobenzene 42%^(d) 5 wt % Pd/CaCO₃ bromobenzene  93%^(d)

Example 6

[0246] Heterogeneously Catalysed Reduction of Alkynes

[0247] The palladium catalysts were used as received. Ionic liquid (2ml), 5.5 mg (5 wt % Pd on calcium carbonate, 10 wt % Pd on activatedcarbon, 5 wt % Pd/CaCO₃ lead poisoned), and substrate (substrate/metal˜800/1) were introduced to the autoclave and purged three times withargon. Hydrogen at the desired pressure was introduced and the autoclaveheated to the required temperature. The reaction is left to stir for thedesired time period, upon which the reaction is cooled and the pressurereleased.

[0248] The reaction products were extracted using organic solvent ordistillation, which removes all the organic products whilst maintainingthe catalyst in the ionic liquid. Product selectivities and conversionswere determined using GC-FID.

[0249] Table 14 shows the conversion and selectivity for the reductionof 1-nonyne using 10% Pd/C and 5% Pd/CaCO₃ in a series of differentalkyl chain length [Pyridinium]⁺ [BF₄]⁻ ionic liquids TABLE 14 Reductionof 1-nonyne using 5 wt % Pd/CaCO₃ and 10 wt % Pd/C at 30° C. and 3 × 10⁵Pa for 4 hours. Catalyst & Ionic Liquid Nonyne Nonene Nonane 10 wt %Pd/C & C₄PyBF₄ 0% 0% 100% 10 wt % Pd/C & C₆PyBF₄ 0% 0% 100% 10 wt % Pd/C& C₈PyBF₄ 0% 0% 100%  5 wt % Pd/CaCO₃ & C₄PyBF₄ 20% 0% 80%  5 wt %Pd/CaCO₃ & C₆PyBF₄ 45% 55% 0%

[0250] Table 14 shows that 10 wt % Pd/C gives complete reduction to thealkane after four hours. The kinetic graph in FIG. 8 shows that 10 wt %Pd/C is 100% selective, although only at low conversions. The 5 wt %Pd/CaCO₃/C₆PyBF₄ system, shows 100% selectivity towards the alkene up toat least 55% conversion, although the C₄ pyridinium BF₄ shows lowerselectivity after 4 h under these reaction conditions. Table 15 showsthe conversion and selectivity for the reduction of three differentsubstrates using the 5 wt % Pd/CaCO₃/C₆PyBF₄ system. TABLE 15 Reductionsof different substrates using 5 wt % Pd/CaCO₃ at 30° C. & 3 × 10⁵ Pa for4 hrs. Catalyst and Ionic Liquid Substrate Conversion Selectivity 5 wt %Pd/CaCO₃ & C₆PyBF₄ 1-nonyne 55 100 5 wt % Pd/CaCO₃ & C₆PyBF₄3-nonyn-1-ol 11 100 5 wt % Pd/CaCO₃ & C₆PyBF₄ Phenyl 75  94 Acetylene

[0251] Table 15 shows that high selectivity towards the alkene isachievable for all three substrates. The conversion and selectivity ofphenyl acetylene towards styrene for a series of experiments varying thereaction pressure, temperature and length of reaction time are shown inFIGS. 9a, 9 b and 9 c.

[0252] The graphs of temperature and pressure shown in FIGS. 9a and 9 bindicate that an increase in either the temperature or pressure has theeffect of increasing the conversion but decreasing the selectivity.

[0253]FIG. 9c shows that when the reaction proceeds for longer thanthree hours, the selectivity drops off dramatically due to furtherhydrogenation to ethyl benzene, indicating that the only way to achievemaximum selectivity is to keep the reaction time and subsequently thelevel of conversion low. The inverse behaviour of the selectivity withrespect to the conversion, explains why as of yet there are noconditions found where 100% conversion and 100% selectivity can beachieved.

[0254] Table 16 shows the reduction of phenyl acetylene in a range ofionic liquids using 5 wt % Pd/CaCO₃ poisoned with lead (Lindlarscatalyst). TABLE 16 Reductions of phenyl acetylene using LindlarsCatalyst at 30° C. and 5 × 10⁵ Pa for 4 hours. Catalyst & Ionic LiquidPhenyl Acetylene Styrene Ethyl Benzene C₁₀mim BF₄ 43% 57% 0% C₈mim BF₄45% 55% 0% C₆Py NTf₂ 75% 25% 0% C₈mim NTf₂ 17% 83% 0% C₆mim NTf₂  3% 97%0% Bmim NTf₂  0% 92% 8%

[0255] Lindlars catalyst maybe used in conjunction with range of ionicliquids to achieve at least 97% conversion with 100% selectivity for thereduction of phenyl acetylene to styrene.

CONCLUSION

[0256] Ionic liquids provide a medium for heterogeneously catalysedhydrogenations, which competes well with conventional solvents. Usingunmodified carbon or oxide based platinum group metal catalysts, goodselectivity to a range of products is achievable simply by selecting aparticular ionic liquid. In these systems it is believed that the ionicliquid modifies the surface and allows the high selectivity to beachieved. Aside from the high selectivity, the use of ionic liquids forhydrogenation reactions provide other advantages over conventionalsolvents, such as the ease of extraction of the product molecule fromthe ionic liquid without the need to filter and reactivate the catalyst.This procedure leads to catalyst loss industrially and is a major safetyhazard when used on a large scale. The ionic liquid based heterogeneouscatalyst systems do deactivate significantly during the reactioncompared with organic solvent systems. In these reactions, the ionicliquids cannot be treated as general solvents, as different ionicliquids promote different selectivities, which allows good control overthe products without the need to change the catalyst.

1. A process for the catalytic hydrogenation of a compound containing at least one unsaturated carbon-carbon bond, said process comprising reacting said compound with a hydrogenating agent and a heterogeneous hydrogenation catalyst in the presence of an ionic liquid.
 2. A process according to claim 1 wherein the compound contains at least one C═C or C≡C bond.
 3. (Cancelled).
 4. (Cancelled).
 5. (Cancelled).
 6. (Cancelled).
 7. A process according to claim 1 wherein the compound contains from 2 to 50 carbon atoms.
 8. (Cancelled).
 9. (Cancelled).
 10. A process according to claim 1 wherein the compound includes a moiety selected from alkenes, alkynes, esters, ethers, carboxylic acids, amines, amides, alcohols, nitrites, aldehydes and ketones; or where the compound is selected from fatty acids and esters thereof, steroids, prostaglandins, isoprenoids, flavonoids icosanoids and compounds containing an aromatic moiety.
 11. (Cancelled).
 12. A process according to claim 1 wherein the compound has the formula:

wherein: R¹ is selected from hydrogen or C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl wherein said alkyl or cycloalkyl group may be substituted with 1-3 substituents independently selected from: C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈ cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆ dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R₃ is selected from H, C₁ to C₂₀ alkyl and C₆ to C₁₀ aryl; or C6 to C₁₀ aryl wherein said aryl group may be substituted with 1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl, F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H, C₁ to C₂₀ alkyl; and R² represents C₁ to C₂₀ straight chain or branched alkenyl or C₅ to C₈ cycloalkenyl wherein said alkenyl or cycloalkenyl group may be substituted with 1-3 substituents independently selected from C₁ to C₂₀ alkyl, C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈ cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆ dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁ to C₂₀ alkyl and C₆ to COO aryl; or C₆ to C₁₀ aryl wherein said aryl group may be substituted with 1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl, F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H, C₁ to C₁ alkyl.
 13. (Cancelled).
 14. A process according to claim 1 wherein the compound has the formula:

wherein: R¹ is selected from hydrogen; C₁ to C₁₀ straight chain or branched alkyl; and R² represents C₁ to C₂₀ straight chain or branched alkenyl or C₅ to C₈ cycloalkenyl wherein said alkenyl or cycloalkenyl group may be substituted with 1-3 substituents independently selected from C₁ to C₂₀ alkyl or C₆ to C₁₀ aryl.
 15. (Cancelled).
 16. A process according to claim 1 wherein the compound comprises an α,β-unsaturated carbonyl moiety.
 17. A process according to claim 1 wherein the compound is cinnamaldehyde, 2 -octenal, methylvinylketone, 3-cyclohexene-1-carboxaldehyde and berizylidine acetone.
 18. A process according to claim 1 wherein the compound has the formula:

wherein: R⁵, R⁶, R⁷ and R⁸ may be the same or different and each is independently selected from: hydrogen; C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl wherein said alkyl or cycloalkyl group may be substituted with 1-3 substituents independently selected from: C2 to C₁₀ alkenyl, C5 to C₈ cycloalkenyl, C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈ cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆ dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁ to C₂₀ alkyl and C₆ to C₁₀ aryl; C₂ to C₂₀ straight chain or branched alkenyl; C₅ to 08 cycloalkenyl; or C₆ to C₁₀ aryl wherein said aryl group may be substituted with 1-3 substituted independently selected from C₁ to C₁₀ alkyl, hydroxyl, F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H and C₁ to C₂₀ alkyl.
 19. (Cancelled).
 20. A process according to claim 1 wherein the compound has the formula:

wherein R⁵, R⁶, R⁷ and R⁸ are the same or different and each is independently selected from: hydrogen; C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl; and C₂ to C₂₀ straight chain or branched alkenyl.
 21. (Cancelled).
 22. A process according to an claim 20 wherein R⁵ and R⁷ each represents hydrogen.
 23. A process according to claim 20 wherein R⁵ and R⁷ are each independently selected from C₁ to C₂₀ straight chain or branched alkyl, C₃ to C₈ cycloalkyl and C₂ to C₂₀ straight chain or branched alkenyl.
 24. (Cancelled).
 25. A process according to claim 1 wherein the compound has the formula:

wherein R⁵, R⁶ and R⁷ may be the same or different and each is independently selected from: hydrogen; C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl wherein said alkyl or cycloalkyl group may be substituted with 1-3 substituents independently to C₆ dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁ to C₂₀ alkyl and C₆ to C₁₀ aryl; C₂ to C₂₀ straight chain or branched alkenyl; C₅ to C₈ cycloalkenyl; or C₆ to C₁₀ aryl wherein said aryl group may be substituted with 1-3 substituted independently selected from C₁ to C₁₀ alkyl, hydroxyl, F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H and C₁ to C₂₀ alkyl.
 26. (Cancelled).
 27. A process according to claim 1 wherein the compound has the formula: R⁹C═CR¹⁰ wherein R⁹ and R¹⁰ are each independently selected from: hydrogen; C₁ to O₂₀ straight chain or branched alkyl or C₃ to CB cycloalkyl wherein said alkyl or cycloalkyl group may be substituted with 1-3 substituents independently selected from: C₂ to C₁₀ alkenyl, C₅ to C₈ cycloalkenyl, C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈ cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆ dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁ to C₂₀ alkyl and C₆ to C₁₀ aryl; and C₆ to C₁₀ aryl wherein said aryl group may be substituted with 1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl, F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H and C₁, to C₂₀ alkyl.
 28. (Cancelled).
 29. A process according to claim 1 wherein: the compound has the formula R⁹C≡CR¹⁰ wherein R⁹ and R¹⁰ are each independently selected from: hydrogen; C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl; and C₆ to C₁₀ aryl wherein said aryl group may be substituted with 1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl, F or OR⁴ wherein R⁴ is selected from H and C₁ to C₂₀ alkyl.
 30. (Cancelled).
 31. (Cancelled).
 32. (Cancelled).
 33. A process for the hydro-dehalogenation of a compound containing at least one C—CI, C—Br or C—I bond, the process comprising reacting said compound with a hydrogenating agent and a heterogeneous hydrogenation catalyst in the presence of an ionic liquid.
 34. A process according to claim 33 wherein the compound has the formula: P-X wherein: P represents a group selected from: C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl wherein said alkyl or cycloalkyl group may be substituted with 1-3 substituents independently selected from: C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈ cycloalkyl, hydroxyl, F, CF₃, ═O, C₁ to C₆ alkylamino, C₁ to C₆ dialkylamino, —CN, COOR³, CONR³ or OR³ wherein R³ is selected from H, C₁ to C₂₀ alkyl and C₆ to C₁₀ aryl; C₆ to C₁₀ aryl wherein said aryl group may be substituted with 1-3 substituents independently selected from C₁ to C₁₀ alkyl, hydroxyl, F, CF₃, CN, COOR⁴, CONR⁴ or OR⁴ wherein R⁴ is selected from H and C₁ to C₂₀ alkyl; heteroaryl; or heterocycloalkyl; and X represents CL, Br or I
 35. A process according to claim 33 wherein the compound has the formula P-X wherein P represents: C₁ to C₂₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl wherein said alkyl or cycloalkyl group may be substituted with 1-3 substituents independently selected from: C₆ to C₁₀ aryl, C₈-C₂₀ aralkyl, C₈-C₂₀ alkaryl, C₃ to C₈ cycloalkyl, hydroxyl; C₈ to C₁₀ aryl wherein said aryl group may be substituted with 1-3 substituents independently selected from C₁ to C₁₀ alkyl, or hydroxyl; heteroaryl; or heterocycloalkyl and X represents Cl, Br or I.
 36. (Cancelled).
 37. A process according to claim 33 wherein the compound contains at least one C—CI bond.
 38. A process according to claim 33 wherein the ionic liquid is an imidazolium, pyridinium, pyridazinium, pyrazinium, oxazolium, triazolium or pyrazolium salt.
 39. A process according to claim 38 wherein the ionic liquid is a salt of an alkylated or polyalkylated compound of pyridine, pyridazine, pyrimidine, pyrazire, imidazole, pyrazole, oxazole or triazole.
 40. A process according to claim 33 wherein the ionic liquid has the formula:

wherein R^(a) is a C₁ to C₄₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl group, wherein said alkyl or cycloalkyl group which may be substituted by one to three groups selected from: C₁, to C₆ alkoxy, C₆ to C₁₀ aryl, CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃₀ alkaryl; R^(b), R^(c), R^(d), R^(e) and R^(f) can be the same or different and are each independently selected from H or any of the R^(a) groups as defined above; and A represents an anion having a charge n−; wherein n may be 1-3.
 41. A process according to claim 40 wherein R⁶ represents C⁴ to C¹² straight chain or branched alkyl.
 42. A process according to claim 40 wherein R^(b), R^(c), R^(d), R^(e) and R^(f) are hydrogen.
 43. (Cancelled).
 44. A process according to claim 33 wherein the ionic liquid has the formula:

wherein each R^(a) may be the same or different and each is independently selected from C₁ to C₄₀ straight chain or branched alkyl which may be substituted by one to three groups selected from: C₁ to C₆ alkoxy, C₈ to C₁₀ aryl, CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃₀ alkaryl; A represents one or more species of anion having valency n; and n represents 1-3.
 45. A process according to claim 33 wherein the ionic liquid has the formula:

wherein R^(a) is selected from C₁ to C₄₀ straight chain or branched alkyl which may be substituted by one to three groups selected from: C₁ to C₈, alkoxy, C₆ to C₁₀, aryl, CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃₀ alkaryl; A represents one or more species of anion having valency n; and n represents 1-3.
 46. A process according to claim 40 to claim 45 wherein R^(a) is independently selected from C₁ to C₄₀ straight chain or branched alkyl.
 47. (Cancelled).
 48. A process according to claim 40 wherein each R^(a) and R^(b) is independently selected from C₄ to C₁₂ straight chain or branched alkyl.
 49. A process according to claim 40 wherein A represents a single species of anion having valency n.
 50. A process according to claim 40 wherein n is
 1. 51. A process according to claim 40 wherein A represents an anion selected from boron or phosphorus fluorides, NO₃, SO₄, HSO₄, HCO₃, [(CF₃SO₂)₂N], [AsF₆], alkylsulfonates, mono- or difluorinated alkyl sulfonates including perfluorinated alkylsulfonates, carboxylic acid anions, fluorinated carboxylic acid anions and metal halides.
 52. (Cancelled).
 53. (Cancelled).
 54. A process according to claim 40 wherein A represents an anion selected from [PF₆], [BF₄] and [(CF₃SO₂)₂N].
 55. (Cancelled).
 56. A process according to claim 33 wherein the heterogeneous hydrogenation catalyst comprises nickel, palladium, ruthenium, iridium, rhodium and platinum.
 57. (Cancelled).
 58. A process according to claim 33 wherein the catalyst is supported on an inert support.
 59. A process according to claim 33 wherein the inert support comprises activated carbon, alumina, silica, silica-alumina, carbon black, graphite, titania, zirconia, calcium carbonate, and barium sulfate.
 60. (Cancelled).
 61. A process according to claim 33 wherein the particle size of the heterogeneous hydrogenation catalyst is up to 200 A.
 62. (Cancelled).
 63. A process according to claim 33 wherein the catalyst particle size, including support (if any) is greater than 20, preferably greater than 50, and preferably greater than 100 μm.
 64. A process according to claim 33 wherein the hydrogenating agent is molecular hydrogen, molecular deuterium, HD, molecular tritium, HT, DT, or an organic or inorganic hydrogen, deuterium or tritium transfer agent.
 65. (Cancelled).
 66. A process according to claim 33 wherein the hydrogenating agent is molecular hydrogen.
 67. A process according to claim 1 wherein the ionic liquid is an imidazolium, pyridinium, pyridazinium, pyrazinium, oxazolium, triazolium or pyrazolium salt.
 68. A process according to claim 1 wherein the ionic liquid is a salt of an alkylated or polyalkylated compound of pyridine, pyridazine, pyrimidine, pyrazine, imidazole, pyrazole, oxazole or triazole.
 69. A process according to claim 1 wherein the ionic liquid has the formula:

wherein R^(a) is a C₁ to C₄₀ straight chain or branched alkyl or C₃ to C₈ cycloalkyl group, wherein said alkyl or cycloalkyl group which may be substituted by one to three groups selected from: C₁ to C₆ alkoxy, C₆ to C₁₀ aryl, CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃₀ alkaryl; R^(b), R^(c), R^(d), R^(e) and R^(f) can be the same or different and are each independently selected from H or any of the R^(a) groups as defined above; and A represents an anion having a charge n−; wherein n may be 1-3.
 70. A process according to claim 69 wherein R^(a) represents C₄ to C₁₂ straight chain or branched alkyl.
 71. A process according to claim 69 wherein R^(b), R^(c), R^(d), R^(e) and R^(f) are hydrogen.
 72. A process according to claim 1 wherein the ionic liquid has the formula:

wherein each R^(a) may be the same or different and each is independently selected from C₁ to C₄₀ straight chain or branched alkyl which may be substituted by one to three groups selected from: C₁ to C₆ alkoxy, C₆ to C₁₀ aryl, CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃ alkaryl; A represents one or more species of anion having valency n; and n represents 1-3
 73. A process according to claim 1 wherein the ionic liquid has the formula:

wherein R^(a) is selected from C₁ to C₄₀ straight chain or branched alkyl which may be substituted by one to three groups selected from: C₁ to C₆ alkoxy, C₆ to C₁₀ aryl, CN, OH, NO₂, C₁ to C₃₀ aralkyl and C₁ to C₃₀ alkaryl; A represents one or more species of anion having valency n; and n represents 1-3.
 74. A process according to claim 69 wherein R^(a) is independently selected from C₁ to C₄₀ straight chain or branched alkyl.
 75. A process according to claim 69 wherein each R^(a) and R^(b) is independently selected from C₄ to C₁₂ straight chain or branched alkyl.
 76. A process according to claim 69 wherein A represents a single species of anion having valency n.
 77. A process according to claim 69 wherein n is
 1. 78. A process according to claim 18 wherein A represents an anion selected from boron or phosphorus fluorides, NO₃, SO₄, HSO₄, HCO₃, [(CF₃SO₂)₂N], [AsF₆], alkylsulfonates, mono- or difluorinated alkyl sulfonates including perfluorinated alkylsulfonates, carboxylic acid anions, fluorinated carboxyic acid anions and metal halides.
 79. A process according to claim 69 wherein A represents an anion selected from [PF₆], [BF₄] and (CF₃SO₂)₂N]
 80. A process according to claim 1 wherein the heterogeneous hydrogenation catalyst comprises nickel, palladium, ruthenium, iridium, rhodium and platinum.
 81. A process according to claim 1 wherein the catalyst is supported on an inert support.
 82. A process according to claim 1 wherein the catalyst is supported on an inert support wherein said inert support comprises activated carbon, alumina, silica, silica-alumina, carbon black, graphite, titania, zirconia, calcium carbonate, and barium sulfate.
 83. A process according to claim 1 wherein the particle size of the heterogeneous hydrogenation catalyst is up to 200 A.
 84. A process according to claim 1 wherein the catalyst particle size, including support (if any) is greater than 20, preferably greater than-50, and preferably greater than 100 μm.
 85. A process according to claim 1 wherein the hydrogenating agent is molecular hydrogen, molecular deuterium, HD, molecular tritium, HT, DT, or an organic or inorganic hydrogen, deuterium or tritium transfer agent.
 86. A process according to claim 1 wherein the hydrogenating agent is molecular hydrogen. 